1. Field of the Invention
The present invention relates to a wafer processing method for dividing a wafer having a microstructure on the front side thereof, and more particularly to a wafer processing method for dividing a MEMS wafer or a CMOS wafer.
2. Description of the Related Art
A wafer having a plurality of MEMS (Micro Electro Mechanical Systems) devices formed on the front side thereof is divided along a plurality of crossing division lines for partitioning these MEMS devices, thereby obtaining a plurality of individual device chips. In the case that such a MEMS wafer is cut by blade dicing, there is a possibility that cutting water may be scattered at the microstructure of the MEMS devices, causing damage to the microstructure. To cope with this problem, there has been proposed a method of dividing a MEMS wafer by attaching a protective tape to the front side of the MEMS wafer and next applying a laser beam to the MEMS wafer from the back side thereof (see Japanese Patent Laid-Open No. 2006-140341, for example).
In the case of cutting a wafer having a plurality of solid-state imaging devices such as CMOS (Complementary Metal Oxide Semiconductor) devices formed on the front side thereof by blade dicing, there is a possibility that a cutting waste or the like may stick to the front side of each device to cause a device failure. To cope with this problem, a cutting method using a protective tape attached to the front side of such a CMOS wafer is also adopted.